The only thing I'm knowledgeable about with these symptoms is the sleep issue, so I'll address that one.
There is a small magnet in the display assembly. This magnet triggers another magnet on the frame, which activates the sleep sensor. Apple shifted a small magnet in the display around between models. If you have both display assemblies still, you can see this by putting the display screen down on a non-scratching surface, and moving a small screw around on the rear bezel of the display until the magnet catches it...they're a few inches different!
Unfortunately, these display assemblies are nearly impossible to put back together cleanly once open (the metal bends or waves, and it looks bad). So I don't have any repair suggestions....just explanations :)